There is very little mass spectrometry performed in the ultra high mass range (>100 kDa). Electrospray ionization and matrix assisted laser desorption ionization were Nobel Prize-winning ideas that enabled mass spectrometry beyond 1,000 Da. This accomplishment sparked a revolution in biomedical science, the ramifications of which are still being felt almost two decades later.
There are three fundamental problems associated with mass spectrometry of ultra high mass species. The first problem involves removal of the enormous amount of kinetic energy imparted to the high mass species in moving them from atmospheric pressure or a condensed matrix into vacuum during the ionization/vaporization process. The second problem is that most mass analyzers are not designed or are physically incapable of working in the ultra high mass range, mass-to-charge ratio >100 kDa. Thirdly, there is a problem with detecting the analytes as they are ejected from the trap over the entire mass range. Detection efficiency decreases with increasing mass above approximately 104 Da.